NEW YORK — Add this one to the presidential collection: the heart-shaped potato.By the time Barack Obama came on stage to the taping of the “Late Show” on Monday, host David Letterman had offered up 10 reasons why in the world the president had agreed to do it.

Among Letterman’s theories: Obama said yes without thinking about it, or as Letterman put it, “Like Bush did with Iraq.”But Obama had other ideas. It turns out he was listening when Letterman had bantered with a woman in the audience who brought — yes — a potato in the shape of a heart to the show.

Obama told Letterman: “The main reason I’m here? I want to see that heart-shaped potato.” The woman tossed the potato to Letterman.She agreed to let Obama keep it. Said the president: “This is remarkable.”

Actually, the Top 10 list was edited out of the broadcast, but it was available on the CBS Web site. A spokesman said the length of the Obama interview caused the edit.Obama also had his most irreverent answer yet on the question of whether some of the vitriolic reaction to his health care plan is driven at least partly by racism.

“First of all, I think it’s important to realize that I was actually black before the election,” Obama said to huge laughs from Letterman and the audience.Responded Letterman: “How long have you been a black man?”Letterman covered a number of topics with Obama — many of them serious — in a taping that ran about 40 minutes. The show will be broadcast on CBS on Monday evening.

On the economy, Obama offered a sober prediction as the country deals with 9.7 percent unemployment, the worst level since 1983. He said he expects unemployment will be a “big problem” for at least another year. But he also said the economy will rebound even stronger.

As for the war in Afghanistan, Obama said he knows some people want him to bring troops home, and others are calling for him to increase U.S. force levels to combat the insurgency. The top U.S. commander there is warning the war could be lost without more troops.

Obama said he won’t make a decision on sending in more troops, though, until he completes a comprehensive review of the war effort and settles on his next strategy.

“I’m going to be asking some very hard questions,” Obama said.Obama’s visit made him the first sitting president to appear on Letterman’s program. He had been on Letterman’s show five times before, though, most recently in September 2008.

The White House said it was a good way for him to reach yet another audience as Obama wraps up a blitz of TV appearances, trying mainly to build support for his health care plan.

As president, Obama also went on NBC’s “Tonight” show when it was hosted by Jay Leno.

After the taping, the president returned to his midtown Manhattan hotel and quietly emerged a while later in gym clothes and a baseball cap. His destination: the church across the street for some basketball with his aides.

Tomorrow starts Obama’s main mission in New York: His participation in the United Nations General Assembly.

David Letterman is in the hot seat for several crude jokes he made on CBS’ “The Late Show” about Sarah Palin and her teenage daughter.

Letterman, in his monologue Tuesday night, noted that the 2008 Republican vice presidential candidate attended a Yankees game during a trip to New York City, where she was honored by a special needs group. Letterman referred to Palin, Alaska’s governor, as having the style of a “slutty flight attendant.”

The “Late Show” host also took a shot Palin’s daughter, while poking fun at the Yankees’ third baseman.”One awkward moment for Sarah Palin at the Yankee game,” Letterman said, “during the seventh inning, her daughter was knocked up by Alex Rodriguez.”

The backlash was almost immediate, with Palin’s supporters denouncing the CBS host for making jokes that many said were sexist and for what they called an unfair attack on the governor and her family.”I think that calling the former vice presidential candidate a slut or saying that her daughter was knocked up by Alex Rodriguez, I think everyone can agree that’s over the line,” Washington Examiner correspondent Byron York told FOX News’ Greta Von Susteren.

But an even more disturbing fact, which Letterman may not have known, was that the daughter who accompanied Palin on her trip to New York was 14-year-old Willow — not 18-year-old Bristol, the unwed mother of Palin’s first grandchild.Now, many critics — including the Palins themselves – are slamming Letterman for jokes that they say make light of sexual abuse of an underage girl.In a statement to FOXNews.com, Palin accused Letterman of making “sexually perverted” and “inappropriate” comments that she doubted he would “ever dare make” about anyone else’s daughter.

“Acceptance of inappropriate sexual comments about an underage girl, who could be anyone’s daughter, contributes to the atrociously high rate of sexual exploitation of minors by older men who use and abuse others,” she said.Palin’s husband, Todd, echoed her sentiments, telling FOXNews.com, “Any ‘jokes’ about raping my 14-year-old are despicable. Alaskans know it, and I believe the rest of the world knows it, too.”A representative for “The Late Show” declined to offer comment for this story.